Ouar. X. DIRECTION OF INFLECTED TENTACLES. 243 
that is, if the stimulus has been sufficient and not 
injurious. Now, when the glands of the disc are 
excited, the exterior tentacles are affected in exactly 
the same manner: the aggregation always com- 
mences in their glands, though these have not been 
directly excited, but have only received some influ- 
ence from the disc, as shown by their increased acid 
secretion. The protoplasm within the cells immedi- 
ately beneath the glands are next affected, and so 
downwards from cell to cell to the bases of the 
tentacles. This process apparently deserves to be 
called a reflex action, in the same manner as when a 
sensory nerve is irritated, and carries an impression 
to a ganglion which sends back some influence to a 
muscle or gland, causing movement or increased 
secretion; but the action in the two cases is probably 
of a widely different nature. After the protoplasm in a 
tentacle has been aggregated, its redissolution always 
begins in the lower part, and slowly travels up the 
pedicel to the gland, so that the protoplasm last 
aggregated is first redissolved. This probably depends 
merely on the protoplasm being less and less aggre- 
gated, lower and lower down in the tentacles, as can 
be seen plainly when the excitement has been slight. 
As soon, therefore, as the aggregating action altogether 
eases, redissolution naturally commences in the less 
strongly aggregated matter in the lowest part of the 
tentacle, and is there first completed. 
Direction of the Inflected Tentacles—When a particle 
of any kind is placed on the gland of one of the outer 
tentacles, this invariably moves towards the centre of 
the leaf; and so it is with all the tentacles of a leaf 
immersed in any exciting fluid. The glands of the 
exterior tentacles then form a ring round the middle 
part of the disc, as shown in a previous figure (fig. 4, 
